1. Field of the Invention
The present invention relates to an image forming apparatus, such as an electronic copying machine.
2. Description of the Related Art
Conventional electronic copying machines comprise a developing unit for developing an electrostatic latent image formed on a photosensitive drum, a toner resupply unit for resupplying the developing unit with toner, and a control panel for operating the copying machine.
The toner resupply unit includes a toner hopper for storing toner, a toner resupply roller for resupplying with toner in the hopper, as required, i.e. according to the copying frequency, and a suppliable-toner detection switch for detecting the quantity of toner remaining in the toner hopper. The control panel includes, among other things, a display section which indicates a shortage in the amount of toner remaining, in accordance with the detection of such by the suppliable-toner detection switch.
In the case of the above conventional copying machines, the supply of toner to the developing unit ceases once a shortage of toner in the hopper is indicated on the display section. Therefore, if copying continues beyond this point, the copy images obtained will not be of a satisfactory density and contrast.